Sprocket drive



Dec. 4, 1962 H. SHAPIRO 3,066,548 sPRocKET DRIVE Filed Aug. 5. 1960 5)/ H/ A 77' @RA/E K5' HARP/5, /f/Ec/f, RUSSEL/ KERN United dtates Patented Dec. 4, 192552 hee 3,056.545 SFRCKET DRlVE Henry Shapiro, Culver City, Calif., assigner to Waste King Corporation, Los Angeles, Calif., a corporation of California Filed Aug. 5, 196i), Ser. No. 47,746 3 (Ilaims. (Cl. 74E-243) rThis invention relates to an improved sprocket drive of the roller type for moving a strip or tape through a mechanism. Sprocket drives are commonly employed for driving recording strip charts and the like.

Sprocket drives of the roller type are provided with a series of aligned, spaced pins around .the perimeter of the roller and are adapted to drive a tape or strip medium having a series of spaced holes paralleling the length of the strip. The holes of the strip are spaced apart a distance which permits their engagement with the spaced pins of the sprocket drive. Generally at any instance there are several pins in engagement with the holes of the strip. It sometimes happens that the holes in the strip become misaligned with respect to the pins of the roller, with the result that succeeding pins do not come into full engagement with the holes of the strip. Such misalignment results in forces that may deform the holes or possibly tear the strip. As will be apparent, in those cases in which the misalignment is in a sidewise direction, that is, lengthwise of the roller, succeeding pins will likely deform the holes into which they come in partial engagement, rather than move the strip to permit full engagement of the pins and ho-les. This is especially true where the strip is relatively inflexible across its width, as is generally the case. The improved sprocket drive of the invention provides a means for accommodating such sidewise misalignment without damage or distortion to the strip and without the necessity of moving the strip relative to the roller of the sprocket drive. This and other objects, features, and advantages of the invention will be apparent from the annexed specification in which:

FlG. l is a side elevation of the improved sprocket drive of the invention having a roller and peripherally placed sprocket pins, illustrating the manner in which the pins are mounted in the roller to permit their movement lengthwise of the roller axis;

FG. 2 is a cross section of the sprocket drive of FiG. l taken along line 2-2 of that figure, showing further etails of the manner of mounting;

FiG. 3 is an isometric view of the pin employed in the improved sprocket drive of the invention;

FIG. 4 is a cross-sectional view of a pin retainer that may be employed for holding the several pins in place; and

FIG. 5 is an isometric View illustrating the sprocket drive of the invention in driving engagement with a tape medium.

In FIG. l there is illustrated a sprocket drive il@ of the roller type made up of a thin walled, elongated cylinder 12 having two journal members i4 and 1S individually supported at its opposite ends. In the particular embodiment of the sprocket drive il) illustrated, the journal member l5 differs from the other journal member i4 in being hollow along its axis. Two pin retainers i7 and 1S in cooperation with the journal members l-fl and i5 respectively position one of two rows 2li and 2l of driving pins 23 at opposite ends of `the sprocket drive roller lil. Each row and 2i is made up of ten pins which are equally spaced around the periphery of the roller l2., with each pin lying on a radius thereof and all of the pins in each row lying in the same vertical cross-sectional plane of `the roller. The several pins 23 are spaced to successively engage spaced holes 26 of a tape medium :net

29 ('FIG. 5). The pins 23 have a circumferential spacing substantially equal to the linear spacing of the holes 26. The series of spaced holes 26 provided at each side of the tape medium 29 runs parallel to the length of the tape.

Each of the journal members i4 and 15 is formed of a shaft 32 extending outwardly from an enlarged shoulder portion 34. The shoulder portions 34 are pressfitted into the outer ends of the cylinder 12. The shaft 32 at its outer end has a stepped-down outside diameter 35, thus providing an outer shaft portion 37 of reduced diameter, adjoining an inner shaft portion 3S of somewhat larger diameter.

The pin retainers i7 and i8 are alike and each has a collar portion 42 (see FIG. 4) which has an inside diameter slightly larger than the outside diameter of the inner shaft portion 3d of the journal member to which it is secured by a locking pin rlhe locking pin 44 extends through a hole 45' in the collar portion 42 and into a registering hole 47 in the inner shaft portion 38. Adjoining each collar portion t2 is a second portion 49 which has a considerably larger inside diameter than the collar. This second portion 49 is provided with ten longitudinal slots Si which deine a like number of equally spaced fingers 52. Thecollar portion d?. and the adjoining second portion 49 of each pin retainer are separated by a perpendicular wall 53 which wall, as best illustrated in FlG. 4, carries an annular groove S4. A perpendicular separating Wall 55 between the shaft 32 and the enlarged shoulder 34 of each of the: journal members 14 and l5 is provided with a similar annular groove 56 of the same cross-sectional dimension and the same diameter as the annular groove 54 of the pin retainer.

With reference to FIGS. 2 and 3, it will be seen that each of the several pins 23 has a length somewhat greater than its breadth and that each is provided with a round bottom 58. Each pin 23 possesses a peripheral groove @il with inwardly sloping sides 6l, placed somewhat closer to the bottom of the pin than to its top. The pin will normally have a circular cross section. ln the particular embodiment illustrated, the upper end of the pin has a tapering cross section, terminating in a blunt end 63.

Means are provided for resiliently mounting the several spaced pins 23 of the two rows Ztl and 2l in a fashion to permit their limited individual movement in a direction parallel to the axis of the roller. This arrangement facilitates the engagement of the pins with the holes 26 of the tape medium 29 upon misalignment of the tape with respect to the roller. In the embodiment illustrated, this resilient means for mounting the pins 23 comprises a pair of identical O-rings 66 and 67 made of rubber or a rubber-like material. Each ring 66 and 67 has a cross section that permits the ring to be snugly fitted into one or the other of the respective grooves 54- and S5 of the pin retainers i7, l o-r journal members ld, 15, The outside diameter of the two O-rings 66 and 67 is somewhat less than the outside diameter of the roller l2.

In the assembled sprocket drive Ell, the several pins 2&3 rest with their round bottoms 58 on the inner shaft portions 33 of the respective journal members 14 and l5.

he several pins 23 are held upright in their respective slots Si of the pin retainer by the two rubber O-rings do and s67 which are spaced on opposite sides of the several pins in contact with their respective peripheral grooves 6i). The two rubber rings 65 and 67 by engaging opposite sides of the respective grooves 6l) of the several pins 23 serve to resiliently limit the movement of the pins lengthwise of the roller. Each of the several pins 23 in being loosely fitted in slots 553i and in contact with the abutting rings 66 and 67, as well as the seating surface of the inner shaft portion 33, is free to move lengthwise 9 d) of the roller to a limited extent by tilting on its round bottom 58. With reference to FIG. 5, it will be seen that this resilient means for mounting the pins 23 permits some movement of the pins to pick up misaligned holes 26 of the tape medium 29. The pins 23 by adjusting their locations minimize the likelihood of tape damage due to misalignment of the tape medium with respect to the sprocket drive.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various changes, modifications, and substitutions may be incorporated therein without departing from the spirit of the invention, as dened by the claims which follow.

I claim:

l. A sprocket drive `for a tape medium having a series of spaced holes running parallel the length of said tape, said sprocket drive comprising: a roller; a plurality of round bottom pins equally spaced around .the periphery of the roller with the round bottoms of the several pins being in contact with an outwardly facing seating surface of the roller and each lying on a radius thereof and inthe same cross-sectional plane of said roller, said pins having a circumferential spacing substantially equal to the linear spacing of the holes of said tape and being restrained against circumferential movement with respect l to the roller; and means for resiliently mounting said spaced pins in the roller to permit limited individual movement of the pins lengthwise of said roller.

2. A device in accordance with claim l wherein said means for resiliently mounting the several pins consists of two resilient members formed of rubber, said pins being conned between said two resilient members formed of rubber placed on opposite sides of and in engagement with said pins, said resilient members permitting limited movement of the individual pins.

3. A device in accordance with claim l wherein each pin is provided with a peripheral groove around its breadth; and wherein the resilient mounting means includes a pair of rubber rings, each of said rings having a diameter somewhat less than the outside diameter of the roller, with the two rubber rings engaging opposite sides of the grooves of the several pins to resiliently limit the movement of said pins lengthwise of the roller.

References Cited in the le of this patent UNITED STATES PA'IENTS 2,003,029 Albersheim May 28, 1935 2,452,591 Metzner Nov. 2, 1948 2,724,280 Davidson Nov. 22, 1955 

